package com.demo;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.RandomAccessFile;

/**
 * Created by Colin.hu on 5/15/2017.
 * <p/>
 * 修改文件
 */

public class FileModify {

    /**
     * 读取文件内容
     *
     * @param filePath
     * @return
     */
    public String read(String filePath) {
        BufferedReader br = null;
        String line = null;
        StringBuffer buf = new StringBuffer();

        try {
            // 根据文件路径创建缓冲输入流
            br = new BufferedReader(new FileReader(filePath));

            // 循环读取文件的每一行, 对需要修改的行进行修改, 放入缓冲对象中
            while ((line = br.readLine()) != null) {
                // 此处根据实际需要修改某些行的内容
                if (line.startsWith("a")) {
                    buf.append(line).append(" start with a");
                }
                else if (line.startsWith("b")) {
                    buf.append(line).append(" start with b");
                }
                // 如果不用修改, 则按原来的内容回写
                else {
                    buf.append(line);
                }
                buf.append(System.getProperty("line.separator"));
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            // 关闭流
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    br = null;
                }
            }
        }

        return buf.toString();
    }

    /**
     * 将内容回写到文件中
     *
     * @param filePath
     * @param content
     */
    public void write(String filePath, String content) {
        BufferedWriter bw = null;

        try {
            // 根据文件路径创建缓冲输出流
            bw = new BufferedWriter(new FileWriter(filePath));
            // 将内容写入文件中
            bw.write(content);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            // 关闭流
            if (bw != null) {
                try {
                    bw.close();
                } catch (IOException e) {
                    bw = null;
                }
            }
        }
    }
    public void fileAppender(String fileName,String content) throws IOException{

        BufferedReader reader = new BufferedReader(new FileReader(fileName));
        String line = null;
        // 一行一行的读
        StringBuilder sb = new StringBuilder();
        sb.append(content);
        while ((line = reader.readLine()) != null) {
            sb.append(line);
            sb.append("\r\n");
        }
        reader.close();

        //写回去
        RandomAccessFile mm = new RandomAccessFile(fileName, "rw");
        mm.writeBytes(sb.toString());
        mm.close();
    }

    /**
     * 主方法
     */
    public static void main(String[] args) {
        String filePath = "E:\\acs\\pdf_out\\51box\\12100000000\\2017\\2\\28\\001\\COL28131444199c8rpwr.pdf"; // 文件路径
        FileModify obj = new FileModify();
        obj.write(filePath, obj.read(filePath)); // 读取修改文件
        try {
            obj.fileAppender(filePath, "set a=b \n");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}
